Lubricating oil compositions of alkylpiperazine alkenyl succinimides



United State 3,024,195 Patented Mar. 6, 1932 3,024,195 LUBRICATING OILCOMPGSKTHONS F ALKYL- PIPERAZINE ALKENYL SUCCINIMIDES Alan Y. Drummond,Richmond, Robert G. Anderson, Novato, and Frank A. Stuart, Orinda,Calif, assignors to California Research Corporation, San Francisco,Calif., a corporation of Delaware N0 Drawing. Filed Aug. 24, 1959, er.No. 835,391 9 Claims. (Cl. 252-51.5)

This invention pertains to lubricating oil compositions havingincorporated therein metal-free detergents. These particular metal-freedetergents are N-substituted alkenyl succinimides.

Alkenyl succinic anhydrides and numerous derivatives thereof are wellknown in the art. For example, alkenyl succinic anhydrides in which thealkenyl radical contains from to 20 carbon atoms are taught as corrosioninhibitors in lubricating oil compositions. Also, products obtained byreacting such alkenyl succinic acid anhydrides with non-cyclic monaminesare taught as ferrous corrosion inhibitors for lubricating oilcompositions.

However, the above known alkenyl succinimides are not useful asdetergents in lubricating oil compositions. In contrast thereto, theN-substituted polyamine alkenyl succinimides which are described hereinare new compounds which are useful as detergents in lubricating oilcompositions.

Present day internal combustion engines operate at high speeds and highcompression ratios. When used in the so-called city stop-and-go driving,which includes the greater part of the driving condition for a largepercentage of todays automobiles, the internal combustion engines do notreach the most efficient operating temperature. Under city drivingconditions, large amounts of partial oxidation products are formed, andreach the crankcase of the engine by blowing past the piston rings. Mostof these partial oxidation products are oil insoluble, tending to formdeposits on the various operating parts of the engine, such as thepistons, piston rings, etc. For the purpose of preventing the depositionof these products on the various engine parts, it is necessary toincorporate detergents in the lubricating oil compositions, thus keepingthese polymeric products highly dispersed in a condition unfavorable fordeposition on metals.

For the most part, the various detergents which are added to crankcaseoils to reduce this formation of sludges and varnishes are metal organiccompounds, particularly those compounds wherein the metal is linked toan organic group through an oxygen atom. Although these metal-containingorganic compounds have some effectiveness as detergents for dispersingthe precursors of deposits within the oil itself rather than permittingthem to form added deposits on the engine parts, they have thedisadvantage of forming ash deposits in the engine. These ash depositslower engine performance 2 by fouling spark plugs and valves, andcontributing to preignition.

It is a particular object of this invention to provide lubricating oilcompositions which are compounded with a metal-free detergent.

Therefore, in accordance with this invention, it has been discoveredthat lubricating oil compositions particularly useful for heavy dutyservice are obtained by incorporating N-alkylpiperazine monoalkenylsuccinimides in oils of lubricating viscosity.

By the use of lubricating oil compositions containing the N-substitutedalkenyl succinimides described herein, diesel and gasoline engine partsremain remarkably free of deposits and varnish, even under severeoperating conditions.

The N-alkylpiperazine monoalkenyl succinimides are new compounds of theformula:

wherein R is a hydrocarbon radical having a molecular weight from about400 to about 3000; that is, R is a hydrocarbon radical containing about30 to about 200 carbon atoms; R is a hydrocarbon radical containing from1 to 3 carbon atoms; and R" is hydrogen or a hydrocarbon radicalcontaining from 1 to 3 carbon atoms.

These N-substituted alkenyl succinimides can be prepared by reactingmaleic anhydride with an olefinic hydrocarbon followed by reacting theresulting alkenyl succinic anhydride with an N-(p-aminoalkyl)piperazine. Such N-(B-aminoalkyl) piperazines are exemplified byN-methyl-N-(fi-aminoethyl) piperazine, N-isopropyl-N'- (fiaminoethyl)piperazine, N-(B-aminoisopropyl) piperazine, etc.

The R radical of the above formula, that is, the alkenyl radical, isderived from an olefin containing from 2 to 5 carbon atoms. Thus, thealkenyl radical is obtained by polymerizing an olefin containing from 2to 5 carbon atoms to form a hydrocarbon having a molecular weightranging from about 400 to about 3000, more preferably, 900 to 1200. Sucholefins are exemplified by ethylene, propylene, l-butene, Z-butene,isobutene, and mixtures thereof. Since the methods of polymerizing theolefins to form polymers thereof is immaterial in the formation of thenew compound described herein, any of the numerous processes availablecan be used therefor.

The preparation of N-substituted monoalkenyl succinimides derived fromamine derivatives of piperazine can be described generally by thefollowing equations, using a polymer of isobutene as an example of thealkenyl radical; and N-(fi-aminoethyl) piperazine as an example of anN-(aminoalkyl) piperazine:

wherein n has a value of about 7 to about 50.

The above reaction between a polyolefin and maleic anhydride is anuncatalyzed addition reaction which should not be confused with acopolymerization reaction such as that obtained with a vinyl monomer andmaleic anhydride. While the general reaction of an olefin and maleicanhydride is well known for olefins of low molecular weight (e.g.,olefin-s of 18 carbon atoms), no previous work has been done with maleicanhydride and the high molecular weight olefins as described herein.

The reaction set forth and described by Equation I hereinabove canproceed in a mol ratio of the polyolefin to the maleic anhydride of 1:1to 1:10, preferably from 1: 1 to 1:5. The reaction temperature can varyfrom 300 F. to 450 F. Because of the greater yield of products obtainedthereby, it is preferred to use the high range of temperatures (e.g.,375 to 450 F.).

In the second step of the reaction as exemplified by Equation IIhereinabove, the yield of the imide is extremely high even though thereactants are used in equal molor ratios.

The reaction described by Equation II hereinabove can be made at 220 F.to 500 F., preferably from 300 F. to 400 F. The alkenyl succinicanhydride and the N-alkylaminepiperazines are reacted in about equalmolar quantities.

Since the reaction between the polyolefin and maleic anhydride may notgo to completion, the resulting alkenylsuccinic anhydride may containsome unreacted polyolefin. As it may not be desirable to separate outthis unreacted polyolefin at this stage, the resulting imide formed byreaction of the alkenyl succinic anhydride and the diamine will containthis polyolefin as an impurity which can be a diluent in the formationof lubricating oil compositions. However, if it is so desired, thisunreacted polyolefin' can be removed by precipitation, for example, byacetone or methanol from a hydrocarbon solution.

Lubricating oils which can be used as base oils include a wide varietyof lubricating oils, such as naphthenic base, paraifin base, and mixedbase lubricating oils, other hydrocarbon lubricants, e.g., lubricatingoils derived from coal products, and synthetic oils, e.g., alkylenepoly- .mers (such as polymers of propylene, butylene, etc., and themixtures thereof), alkylene oxide-type polymers (e.g., propylene oxidepolymers) and derivatives, including alkylene oxide polymers prepared bypolymerizing the alkylene oxide in the presence of water or alcohols,e.g'., ethyl alcohol, dicarboxylic acid esters (such as those which areprepared by esterifying such dicarboxylic acids as adipic acid, azelaicacid, suberic acid, sebacic acid, alkanol succinic acid, furnaric acid,maleic acid, etc., with alcohols such as butyl alcohol, hexyl alcohol,2-ethyl hexyl alcohol, dodecyl alcohol, etc.), liquid esters of acids ofphosphorus, alkyl benzenes (e.g., monoalkyl benzene such as dodecylbenzene, tetradecyl benzene, etc., and dialkyl benzenes (e.g., nnonyl2-ethyl hexyl benzene); polyphenyls (e.g., biphenyls and terphenyls),alkyl biphenyl ethers, polymers of silicon (e.g., tetraethyl silicate,tetrai-sopropyl silicates, tetra-(4-methyl-2-tetraethyl) silicate, hexyl(4-methyl-2-pentoxy) disiloxane, poly(rnethyl) siloxane,poly(methylphenyl) siloxane, etc. Synthetic oils of the alkyleneoxide-type polymers which may be used include those exemplified by thealkylene oxide polymers.

The above base oils may be used individually or in combinations thereof,wherever miscible or Wherever made so by the use of mutual solvents.

The above-described alkenyl succinimides of this in vention can be usedin oils of lubricating viscosity in amounts of 0.1% to by weight,preferably 0.25% to 5%, by weight.

The preparation of N-alkylpiperazine alkenyl succinimides is illustratedin the following examples.

EXAMPLE I.-PREPAR ATION OF POLYBUTENYL SUCCINIC ANHYDRIDE A mixture of1000 grams (1 mol) of a polybutene having a molecular Weight of about1000 and 98 grams (1 mol) of maleic anhydride was heated at 410 F. in anitrogen atmosphere with agitation for a period of 24 hours. Thereaction mixture was cooled to 150 F. and 700 cc. of hexane added; afterwhich the mixture was filtered under vacuum. After vacuum distillationto remove the hexane from the filtrate, the product was maintained at350 F. atan absolute pressure of 10 mm. Hg for one hour to remove tracesof maleic anhydride. The crude polybutenyl succinic anhydride thusprepared had a saponification number of 79.

EXAMPLE lI.-PREPARATION OF N-ETHYLPIPER- AZINE POLYBUTENYL SUCCINIMIDEANHY- DRIDE A mixture of 18 grams (0.14 mol) of N-(fl-aminoethyl)piperazine and 200 grams (0.127 mol) of the polybutenyl succinicanhydride of Example I hereinabove was blended with agitation in anitrogen atmosphere. The mixture was heated at 500 F. for one hour,after which the absolute pressure was reduced to about 200 mm. Hg tofacilitate the removal of water and unreacted piperazine. The reactionmixture was then allowed to reach room temperature at this reducedpressure. The reaction product contained 2.59% nitrogen (theory=2.67%).Infrared analysis showed that the reaction product was an imidecontaining a polybutene side chain.

Table I hereinbelow presents data obtained with lubricating oilcompositions containing N-alkylpiperazine monoalkenyl succinimides.

The tests were made in a Caterpillar L-1 engine according to MilL-2104conditions for a period of .120 hours as described in the CoordinatingResearch Council Handbook, January 1946.

The PD Nos. refer to the piston discoloration rating. After the enginetest, the three piston lands are examined visually. To a piston skirtwhich is completely black is assigned a PD number of 800; to one whichis completely clean, a PD number of 0; to those intermediate betweencompletely black and completely clean are assigned PD numbersintermediate in proportion to the extent and degree of darkening.

The GD Nos. refer to the percentage deposits in the piston ring grooves;and 0 evaluation being a clean groove; and a number of being a groovefull of deposits.

The base oils were California SAE 30 base oils.

Table I Additive A B C Sueclnimide, weight percent 0. 1.0 1.0Dithiophosphate;mM./kg 0. 0 0. 0 12 st Results:

GD N o 39 1 0.3 PD N0 800, 800, 800 25, 0, 5 10, 0, 0

Table II hereinbelow presents data obtained in an FL2 test, using a6-cylinder Chevrolet engine operating at 2500 r.p.m. for a period of 40hours, which test is fully described in a Coordinating Research Councilbulletin titled Research Technique for the Determination of the Elfectsof Fuels and Lubricants on the Formation of Deposits During ModerateTemperature Operation (1948).

The piston varnish rating is a visual observation of the amount ofvarnish on a piston skirt, with 10 being the maximum rating for aperfectly clean piston and a 0 being the rating of a piston fullycovered with black varnish. This piston varnish rating correlates withroad performance in automobiles.

The base oil was an SAE 30 base oil.

The succinimide and the dithiophosphate were the same as those describedfor Table I hereinabove.

It is readily seen from the data set forth hereinabove in Tables I and-II that lubricating oil compositions containing the N-alkylpiperazinealkenyl succinimides as described herein are superior as lubricating oilcompositions for the lubricating of internal combustion engines.

vIn addition to the dithiophosphate described hereinabove, lubricatingoil compositions containing the N-substituted alkenyl succinimides ofN-alkylpiperazine of this invention may also contain other detergents,viscosity index improving agents, rust inhibitors, oiliness agents,grease thickening agents, etc.

We claim:

1. A lubricating oil composition consisting essentially of an oil oflubricating viscosity and from 0.1% to 80%, by Weight, of anN-alkylpiperazine monoalkenyl succinimide of the formula:

wherein R is a hydrocarbon radical having a molecular weight from about400 to about 3000, and R is a hydrocarbon radical containing from 1 to 3carbon atoms.

2. A lubricating oil composition consisting essentially of an oil oflubricating viscosity and from 0.1% to by weight, of anN-alkylpiperazine monoalkenyl succinimide of the formula:

wherein R is a hydrocarbon radical having a molecular weight from about900 to about 1200, and R' is a hydrocarbon radical containing from 1 to3 carbon atoms.

3. A lubricating oil composition comprising a major proportion of an oilof lubricating viscosity and firom 0.25 to 5%, by weight, of anN-alkylpiperazine monoalkenyl succinimide of the formula:

wherein R is a hydrocarbon radical having a molecular weight from about900 to about 1200, and R is a hydrocarbon radical containing from 1 to 3carbon atoms, and R" is selected from the group consisting of hydrogenand hydrocarbon radicals containing from 1 to 3 carbon atoms.

4. A lubricating oil composition comprising a major proportion of apetroleum lubricating oil and from 0.25% to 5%, by weight, of anN-substituted monoalkenyl succinimide of the formula:

CH; CH;

CHz-CH: CHa/n CHICHQN NH GHQ-T"? CHPCHI wherein n has a value of about 7to about 5 0.

5. A lubricating oil composition comprising a major proportion of an oilof lubricating viscosity and a minor proportion, in an amount sufiicientto impart detergency to said oil, of an N-alkylpiperazine monoalkenylsuccinim ide of the formula:

wherein R is a hydrocarbon radical having a molecular weight from about400 to about 3,000, R is a hydrocarbon radical containing from one tothree carbon atoms, and R" is selected from the group consisting ofhydrogen and hydrocarbon radicals containing from 1 to 3 carbon atoms.

6. A lubricating oil composition comprising a major proportion of an oilof lubricating viscosity and a minor proportion, an amount sufiicient toimpart detergency to said oil, of an N-alkylpiperazine monoalkenylsuccinimide of the formula:

wherein R is a hydrocarbon radical containing from about 30 to about 200carbon atoms formed by polymerizing olefins containing from 2 to 5carbon atoms, and R is a hydrocarbon radical containing from 1 to 3carbon atoms.

7. A lubricating oil composition consisting essentially of an oil oflubricating viscosity and from about 0.1% to about 80%, by weight, of anN-alkylpiperazine monoalkenyl succinimide of the formula:

wherein R is an aleknyl radical containing from 30 to 200 carbon atomsand which is a polymer of an olefin containing from 2 to 5 carbon atoms,and R is an alkyl radical containing from 1 to 3 carbon atoms.

8. A lubricating oil composition comprising a" major C II;

proportion of an oil of lubricating viscosity and from 0.25% to 5%, byweight, of an N-alkylpiperazine monoalkenyl succinimide of the formula:

wherein n has a value of about 7 to about 50.

References Cited in thefile of this patent UNITED STATES PATENTS2,490,744 Trigg et al Dec. 6, 1949 2,604,451 Rocchini July 22, 19522,638,450 White et a1 May 12, 19 52 UNITED STATES PATENT OFFICECERTIFICATION OF CORRECTION Patent No. 3,024,195 March a, 1962 Alan Y.Drummond et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Columns 1 and 2, bottom of the page, the front end portion of thereactant and the reaction product of the equations, and the top ofcolumn 3, two occurrences, should appear as shown below instead of as inthe patent:

H CH3 n column 2, lines 18 to 24, column 5, lines 69 to 75, column 6,lines 8 to 13, lines 21 to 27, lines 49 to 55, lines 67 to 73, column'7, lines 7 to 13, and column 8, lines 4 to 9,

the left-hand portion of the formula, each occurrence, should appear asshown below instead of as in the patent:

SEAL) ittest:

IRNEST W. SWIDER lttesting Officer DAVID L. LADD Commissioner of Patents

1. A LUBRICATING OIL COMPOSITION CONSISTING ESSENTIALLY OF AN OIL OFLUBRICATING VISCOSITY AND FROM 0.1% TO 80%, BY WEIGHT, OF ANN-ALKYLPIPERAZINE MONOALKENYL SUCCINIMIDE OF THE FORMULA: